Diagnosis and Assessment
Figure 1. Influenza Diagnosis
Outside Flu Season
Sx ≤5 d
Febrile
respiratory
Sx linked to
outbreak
Test (if results influence management)
During Flu Season
Sx ≤5 d
Sx of any duration
Febrile
respiratory Sx in
immunocompetent
high-risk patients
Febrile respiratory Sx
after hospitalization
Febrile respiratory
Sx in all children,
inpatients, and
immunocompromised
Elderly and infants
suspected of sepsis
Severe illness with
hypothermia
Test (if results influence management)a
Sx, symptoms.
a
In patients who are hospitalized or at high risk of complications, antiviral therapy should be started
before laboratory test results are available.
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